This project investigates two areas of messenger-RNA structure and function relative to the mechanism of messenger-RNA translation. Specifically: 1) Features of a eucaryotic messenger-RNA that restrict its being "capped" with a 5'-terminal m to the seventh power G(5')ppp(5')Np...group by known capping enzymes are being investigated in order to define how 5'-terminal capping of messenger-RNAs regulates protein synthesis in eucaryotes. 2) The nucleotide sequence about the single site of initiation of translation of the monocistronic eucaryotic message, Satellite Tobacco Necrosis Virus RNA, is being examined in order to define what features of messenger-RNAs are involved in the initiation of translation in protein biosynthesis.